That is their standard response to all floors. Maybe the rare floor finisher uses waterborne poly.
The answer depends on what kind of finish appearance you want, what expectations for wear you have, and how "historical" you may be willing to be.
The list of potential finishes, least-durable (requiring frequent maintenance, but giving a unique and more historically-authentic appearance, to hard, bulletproof plastic-y and inauthentic):
Bare floor: ages naturally, but will water spot and stain most easily. wood worn away by foot traffic, especially with a very soft wood like white pine. No color will be brought out except by passage of time and whatever dirt/patina builds up and as the wood oxidizes.

Wax finish: low protection from water and wear, must be renewed yearly or more, potential to bring out some color in the wood; colored waxes are now readily available. Will be a very authentic soft finish showing much of the natural wood color and texture. Wax does not form a film.

Oil finish: Lots of oils out there, most oil finishes do not form a film, so the wood still looks bare/natural. Colored oil finishes are possible, but may blotch a bit at first, this usually will fade when 100% dry. Water spotting still possible, and wood can still wear down. The wood's surface is still taking the wear, but it has been fortified because the oil has penetrated it. Some harder-drying oils, like 100% tung oil, Australian Timber Oil, and I think Landark, are fairly good at hardening the wood surface and are the most durable oils. Wear spots can usually be masked by the application of more oil as needed.

Shellac is called a "spirit varnish" because it forms it's protective beautifying film by the evaporation of the alcohol solvent that liquefies it. As the alcohol evaporates very quickly, shellac is a fast-drying finish. Some shellacs contain wax as an impurity. It is added as an extender, and it does help somewhat to achieve a smooth rubbed-out finish when buffed with steel wool. The wax/impurity also shortens the shelf life and lengthens the drying time, while making the finish less water-resistant. In my experience, it's the wax that makes shellac get white water spots. I only use de-waxed shellac, which can be purchased ready-mixed (Zinsser Sealcoat) or made by dissolving flakes in alcohol. I use a lot of shellac for various things, including some floors in my house (and fine furniture finishes). The formula I use for floors is to sand to at least 120, with the grain, by hand, then apply two coats of de-waxed garnet shellac (the darkest colored shellac that really brings out the beauty and gives a base color that's very pleasing on old wood/old house context) and put on 4 coats of the Sealcoat for the wear layer. Six coats of garnet to reach the same film thickness would be awfully dark IMO. Scratches in the shellac floor can be easily touched up without the need to sand the whole floor. Shellac will always bond to shellac, so there is never any problems with blistering or peeling. Because shellac has no odor after the alcohol evaporates, and you can put on 4 coats in a day, it's really great for bedrooms or people with chemical sensitivity.

Old-fashion oil varnishes are sometimes used, but the reasons poly is preferred is because it has more benefits for floors because it is harder, so people don't mess with non-poly oil varnish much at all. The only benefit would be that it could theoretically be removed by a chemical stripper so future refinishing would be possible without further sanding. Oil varnish gives a deep amber color to wood, especially your old white pine. Problems include long drying time, softness, difficulty to touch up without sanding. Easier to re-coat than poly, though, because it will stick to itself with lower risk of peeling.

Film-forming oil finishes, like Waterlox, are sometimes the most appropriate non-poly floor finish for historic floors. The huge selling point (what sold me) is the need for no future sanding. As historic flooring fabric is a finite resource, and can only take so much sanding until it is worn beyond use, eventually one must consider replacement vs. conservation. Waterlox makes the case that since it can be scuffed and recoated there is never any need to fully sand the wood, so a stable condition on the old floor can be maintained for a long time.
Waterlox is a thinner oil=based varnish made with tung oil (I can smell it!) along with other resins and solvents. It has a _very_ strong odor when being applied, as you are getting the effect of the solvent and the material all at once. You need an activated charcoal respirator made for VOC's, or you will suffer the effects. It stinks, OK? The curing time, during which the odor can be detected, will be about a month. The bad, toxic aroma is gone in a day or two. I chose Waterlox for my old kitchen floor. It has held up pretty well; it's now been almost 5 years and there are some scuffed-looking areas where the chairs sit. It's been great for spills, water, general traffic, etc. So I recommend it unless you have chemical sensitivities for aromatic organic compounds, or nut allergies (!) Tung oil is from a nut, BTW.

We then come to Polys and other hard commercial-grade floor finishes, some of which are technically difficult to apply and have severe health threats if the proper measures aren't observed while applying. I have such limited experience with any of these that I cannot comment as to any particulars, except to state that they do not have it within themselves to be touched up, and any damage to an area however small usually calls for the whole floor to be re-sanded for a total refinish, or the spot would still be visible. These finishes last an amazingly long time, requiring only cleaning maintenance, and if the floor in question were a new hard wood, it would make the most sense to use the most long-lived finish you could obtain. But in your circumstance it's probably obvious by now that I would not recommend such a finish for your historic wood floor.
Sorry this was so long, but I wanted to weigh all the characteristics within your specific context.
Casey